Working as an electronic pollution eliminator, the Power Factor Corrector's (PFC) own Electromagnetic Interference (EMI) problems have been blocking its performance improvement for long. In this paper, a systematic research on EMI generation of a multi-stage Two-Boost-Circuit Interleaved Bridgeless PFC (IBPFC) is presented. The insight into relationship of interleaving stages, switching on/off oscillations and EMI reduction is discussed. Finally, a 3.5kW universal input 2-stage IBPFC prototype was built to verify the theoretical analysis. Experimental results show that significant EMI reductions at odd harmonics can be achieved by carefully designing the BPFC using interleaving technique.